Publikationsliste Dr. Zhe Shu

• Originalarbeiten in wissenschaftlichen Fachzeitschriften
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Originalarbeiten in wissenschaftlichen Fachzeitschriften

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2024

• D. Straubinger, P. Koltay, R. Zengerle, S. Kartmann, Z. Shu
  Bulge-Free and Homogeneous Metal Line Jet Printing with StarJet Technology
  2024 Micromachines, Band: 15, Seite: 743
• Z. Khan, D. Gururajan, P. Koltay, S. Kartmann, R. Zengerle, Z. Shu
  Hybrid 3D Printing of Molten Metal Microdroplets and Polymers for Prototyping of Printed Circuit Boards Featuring Interdigitated 3D Capacitors
  2024 EEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, IEEJ Trans 2024
• Z. Khan, A. Saphala, S. Kartmann, P. Koltay, R. Zengerle, O. Amft, Z. Shu
  Hybrid Printing of Conductive Traces from Bulk Metal for Digital Signals in Intelligent Device
  2024 Micromachines, Band: 15, Seite: 750
• Z. Khan, D. Gururajan, S. Kartmann, P. Koltay, R. Zengerle, Z. Shu
  Iterative printing of bulk metal and polymer for additive manufacturing of multi-layer electronic circuits
  2024 npj Adv. Manuf., Band: 1, Nummer: 1

2023

• Z. Khan, P. Koltay, R. Zengerle, S. Kartmann, Z. Shu
  One-Stop Hybrid Printing of Bulk Metal and Polymer for 3D Electronics
  2023 Advanced Engineering Materials, Seite: 2300922

2022

• S. Hennig, Z. Shu, L. Gutzweiler, P. Koltay, F. von Stetten, R. Zengerle, S. M. Früh
  Paper-based open microfluidic platform for protein electrophoresis and immunoprobing
  2022 Electrophoresis, Band: 43, Nummer: 4, Seiten: 621 - 631

2020

• Z. Shu, M. Fechtig, F. Lombeck, M. Breitwieser, Roland Zengerle, Peter Koltay
  Direct Drop-on-Demand Printing of Molten Solder Bumps on ENIG Finishing at Ambient Conditions through StarJet Technology
  2020 IEEE Access, Band: 8, Seiten: 210225 - 210233
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  Kurzfassung

  In this paper, we report on a detailed experimental study carried out with the StarJet technology to investigate the mechanical adhesion properties of directly printed solder bumps on electroless nickel immersion gold (ENIG) plated PCB boards. The aim of this study is to determine the maximum bond strength achievable by this method and to find suitable printing parameters that allow for the production of reliable and consistent solder bumps by non-contact printing of molten solder (type SAC305). Molten solder droplets of about 250 μm diameter were printed at melt temperatures between 250 and 400 °C onto ENIG surfaces kept at temperatures in the range of 100 to 200 °C. Using shear force tests, the adhesion of the printed bumps was investigated as a function of the main process parameters: 1. printhead temperature, 2. substrate temperature, and 3. substrate preheating time. The formation of an intermetallic compound (IMC) between the solder and the ENIG was confirmed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) measurements. As a result of the comprehensive experimental parameter study, suitable printing parameters for establishing bond strengths corresponding to maximum shear force values of 3000 to 4000 mN could be found, i.e. high printhead temperature of 400 °C, short preheating and time of < 2 min, and substrate heating at 180 °C The use of flux was found to slightly improve the bond strength and to improve the consistency of the printing results for extended operation times. The achieved high bond strength and the reasonable reproducibility of the printing results qualify the StarJet technology for further investigations regarding applications in the field of direct soldering of microelectronic chips and devices to PCB boards as well as other micro-assembly tasks in the future.

Konferenzbeiträge

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2024

• D. Straubinger, Z. Khan, P. Koltay, R. Zengerle, S. Kartmann, Z. Shu
  Investigation of metal jet printing for homogeneous lines with Starjet technology
  2024 MFHS 2024 - The 5th Conference on Microfluidic Handling Systems, Munich, 21-23 February 2024
• Z. Khan, A. Saphala, D. Straubinger, S. Kartmann, P. Koltay, R. Zengerle, O. Amft, Z. Shu
  Towards hybrid printing of intelligent devices: conductive traces from bulk metal for digital signals
  2024 MFHS 2024 - The 5th Conference on Microfluidic Handling Systems, Munich, 21-23 February 2024

2023

• Z. Shu, S. Hennig, P. Koltay, S. Kartmann, F. von Stetten, R. Zengerle
  Automated sample preparation platform for protein diagnostics based on open microfluidics electrophoresis
  2023 Black Forest Nanopore Meeting, Freiburg, 06.-09.11.2023
• Z. Khan, P. Koltay, R. Zengerle, S. Kartmann, Z. Shu
  Direct conductive metal printing for one step fabrication of hybrid flexible electronics
  2023 inno LAE 2023, Cambridge, UK, 21. – 23. Feb. 2023
• Z. Shu
  Hybrid 3D printing of conductive metal and polymer for smart 3D electronics and sensors
  2023 IVAM Hightech Summit 2023, Bochum, 03.-04.05.2023
• Z. Khan, D. Gururajan, D. Straubinger, P. Koltay, S. Kartmann, R. Zengerle, Z. Shu
  Hybrid 3D-printing of molten metal microdroplets and polymers for prototyping of printed circuit boards with integrated electrical energy storage systems
  2023 Transducers, Kyoto/Japan, May 25-29, 2023
• Z. Shu
  StarJet Technology - Direct molten metal printing for printed, flexible, 3D electronic applications
  2023 TechBlick, virtuell, 29.-30.03.2023

2022

• Z. Khan, R. Zengerle, P. Koltay, S. Kartmann, Z. Shu
  3D printed single-layer functional PCB via digital hybrid printing of polymer and molten metal
  2022 5th International Conference on 3D Printing & Bioprinting, ΑΙ, Digital and Additive Manufacturing (I3D22)
• Z. Khan, P. Koltay, R. Zengerle, S. Kartmann, Z. Shu
  Direct printing of molten solder via StarJet technology in Flexible Hybrid Electronics
  2022 Flex Conference & Expo, San Francisco, USA, July 11-14, 2022
• S. Hennig, Z. Shu, L. Gutzweiler, P. Koltay, F. von Stetten, R. Zengerle, S. M. Früh
  “Paper-based open microfluidics platform for automatic protein analysis
  2022 SLAS Europe 2022 Conference and Exhibition, Dublin, Ireland, May 26, 2022

2021

• Z. Khan, Z. Shu, R. Zengerle, P. Koltay
  Hybrid 3D printing of polymer and solder to create functional 3D electronics
  2021 EPoSS Annual Forum 2021, Freiburg, 04.-07.10.2021

2020

• A. Brunauer, B. Breiner, S. Hennig, D. Kainz, R. Verboket, B. Johannsen, D. Baumgartner, K. Mitsakakis, L. Gutzweiler, Z. Shu, P. Koltay, T. Hutzenlaub, N. Paust, R. Zengerle, F. von Stetten, S. M. Früh
  Actuation principles for bioanalytical platforms to combat infectious diseases
  2020 Virtual EMBL Conference: Microfluidics: Designing the Next Wave of Biological Inquiry 2020, 13.-15.07.2020

2019

• Z. Shu, B. Gerdes, M. Fechtig, R. Zengerle, P. Koltay
  Highly conductive flexible and 3D metallization on flexible and textile substrates via StarJet Technology
  2019 12th International Symposium on Flexible Organic Electronics (ISFOE19) 1-4 July 2019, Thessaloniki, Greece
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  Kurzfassung

  Highly conductive metallizations are crucial for large area organic and printed electronics. State-of-the-art printing technologies such as inkjet printing and screen printing are still facing critical challenges regarding achieving high electrical conductivity and reducing the manufacturing costs. Moreover, additional post-processes such as thermal, photonic or laser sintering are either not compatible with the flexible substrates or expensive. On the contrary, the non-contact StarJet printing technology provides direct metallization from molten metal microdroplets and continuously Jet. It bases on a pneumatically driven printhead that features a heatable reservoir and an interchangeable nozzle chip with a star-shaped orifice geometry. Thanks to the pneumatic driven mechanism, materials with high melting temperature such as solder or aluminium alloys can be printed. Single-pass conductive features, printed via StarJet, exhibit high electrical conductance (7.5 Ω/m for 250 μm linewidth), high aspect ratio, i.e. high layer thickness (70 – 300 μm), and require no post-treatment. Examples of electrically functional, direct metallization were demonstrated on silicon solar cells and PCB boards. In this contribution, we demonstrate that the StarJet technology is also compatible with temperature sensitive flexible substrates such as polymer foils and textiles. The printed solder lines exhibit not only high electrical conductance but also high mechanical stability (i.e. adhesion) and high flexibility. The printed solder lines on polymer foils and textile can stand shear forces of up to 3000 mN and at the same time tolerate substrate bending at the radius of 5 mm. Furthermore, because the printed solder droplets fuse together, freestanding structures with different angles can also be printed via controlling process parameters. In summary, the StarJet technology shows high potential in direct metallization for large area flexible and wearable electronics and 3D electronic applications.

2018

• Z. Shu, B. Gerdes, M. Fechtig, L. Riegger, R. Zengerle, P. Koltay
  Direct Printing of Conductive Metal Lines from Molten Solder Jets via StarJet Technology on Thin, Flexible Polymer Substrates
  2018 NIP & Digital Fabrication Conference, Printing for Fabrication 2018, Dresden, 23. – 27.09.2018 Society for Imaging Science and Technology.
• Z. Shu, B. Gerdes, M. Fechtig, L. Riegger, R. Zengerle, P. Koltay
  Direct Printing of Conductive Metal Lines from Molten Solder Jets via StarJet Technology on Thin, Flexible Polymer Substrates
  2018 NIP & Digital Fabrication Conference, Printing for Fabrication 2018 Society for Imaging Science and Technology, Band: 2018, Nummer: 1, Seiten: 72 - 75
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  Kurzfassung

  We present the direct printing of thin (linewidth of 70 μm) conductive lines from molten solder on thin, flexible substrates. The lines are generated via the so-called StarJet technology that enables the printing of micro jets from molten metal. In this work, metal lines are printed for the first time on flexible substrates, possibly enabling applications in the field of printed electronics. The printed lines are evaluated regarding their mechanical and electrical properties. To the knowledge of the authors, this is the first time that direct printing of a functional metallization, requiring no further treatment, on a flexible polymer substrate was demonstrated. The lines exhibit a low ohmic resistance and can endure shear forces of up to 3.5 N on polyethylene terephthalate (PET) substrates.